Flux for soldering aluminium.



" UN TE S E Patented May 24, 1904.

PATENT ()rFicE,

cA LEToN ELLIS, or BOSTON, MASSACHUSETTS, ASSIGNOR TO NATHANIEL L.FOSTER, TRUSTEE, or BRooKnmE, AssAc ns Ts.

FLUX. FOR ISOLDERING ALUMINIUM.

SPECIFICATION forming part or Letters; Patent no. 766,783, dated Ma 24,1904.

Application filed January 12, 1904.

Tao/ ll whom it may concerm.

. 'Be, it known that I, OARLETON ELLIs, ofBoston, inthe county ofSuffolk and State of Massachusetts, have invented certain new and usefulImprovements in Flux for Soldering Aluminium, of which the following isa specification.

The object of this invention is to provide a flux for solderingaluminium which shall overcome the repellent action of the aluminium andpermit the solder to flow readily over the surface. In United StatesPatent No. 746,802, of December 15, 1903, issued to Carleton Ellis andOwen J. Flanigan, the patentees describe the thermoplating action of thesalts of the heavy metals when used in combination with organic bodiesas a flux for soldering aluminium or beryllium.

The present invention is an improvementon the above-cited patent; and itconsists in the use, withthe heavy metal salts and organic matter, ofvarious salts-or compounds having surface and which thereby assist inremoving the alumina and in aiding the action of thermoplating. A largenumber of compounds act more or less efliciently in this manner. Chiefamong these are the haloid salts of the alkalies or alkaline earthsas,for example, potassium fiuorid or barium bromid. From point is nearlyreached, when the plastic mass may be pressed into the form of sticks orpencils. 1f the mixture is to be applied in paste form, a volatile ornon-volatile solvent may be addedas, for instance, turpentine, alcohol,or paraffin-oil.

I have found in using the heavy metallic compounds in combination withan organic reducing vehicle that the physical state of Serial No.188,'736.. (No specimens) salt is used in a coarse condition, itscovering power is poor and the solder does not always I flow freely.Further, where occasion requires the soldering of a lap-seam,lock-joint, or similar work, wherethe pieces of aluminium are alreadyclosely fitted into place, it is difiicult to work the flux into thejoint.

I have found that if the flux contains the metallic salt in an extremelyfine state of division it becomes much more penetrating and causes thesolder to flow very freely and to unite with the surface in every part.

In carrying out my invention I prefer to prepare the metallic salt in afine state of subdivision and suitably in the following manner: First,precipitation of the salt from very dilute solutions in a lightflocculent condition; second, trituration of the precipitated salt withthe organic compound in a most thorough manner. a cleansing or fluxingaction on the alumlmum The formation and precipitation of the salt ispreferably brought about by'metathetical reaction. When the metallicsalt desired is soluble in water, menstruum a's, for instance, alcoholinwhich the resulting salt is insoluble, may be used.

As an example the following will serve: If silver chlorid be the saltdesired, proceed as follows: One hundred grams nitrate of silver aredissolved in eight liters of water and precipitated in the cold by therequisite amount of hydrochloric acid or by a soluble chlorid. Theprecipitate is. well Washed, and dried, preferably, at about 45centigrade. The wet precipitate may be mixed with the organic compoundWithout'drying; but the flux made in this manner does not afford as goodresults. It is then ground with the organic body and alkali haloid in aporcelain ball mill for twenty-four hours, when the compound is readyfor use as a flux. Such a flux answers all requirements. It admits ofsoldering seams made by folding the metal, cracks in aluminium castings,and other work which has hitherto proven difficult with the salts asordinarily found in commerce. The treated metallic salt is also moreeasily reduced and a has greater covering power; hence is not only moreeffective, but is more economical to use than the unprepared salt.

Employing the finely-divided salt it has been found that one partmetallic salt to ten parts of organic matter was just as effective asone part untreated salt to two parts of organic matter.

' As the organic matter which may be employed is comparativelyinexpensive, a cheapening in the cost of the flux results by the use ofthe salt treated as herein described. 7

My present invention of a flux for soldering aluminium thereforeconsists of the combination of the three following classes ofbodies:

1. A thermoplating compoundi. 6., a finely-divided metallic salt-whoseheat of formation is less than that of the corresponding salt ofaluminium.

2. A detergent or alumina-dissolving com pound embracing salts whoseheat of formation is greater thanthe corresponding salt of aluminium,especially designated being the halogen salts of the alkalies. I I

3. An organic body whose carbon or hydrogen at' elevated temperatures iscapable of acting 'reducingly on the metallic salt in class 1.

In selecting from these classes the individ- 3 =ble at high temperaturesof acting reducingly on the compounds comprised by class 1. For the sakeof cheapness it may be an oil stock or a Wax.

What I claim as my invention is- Flux for soldering aluminium consistingof a heavy metal salt whose heat of formation is less than thecorresponding salt of aluminium, a saline body whose heat of formationis greater than the corresponding salt of aluminium and an organic body.

In testimony whereof I have afiixcd my signature in presence of twowitnesses.

oARLEToN ELLIS.

